My copending application, Ser. No. 587,205, discloses electrical circuitry in which the electrical output from two separate branch outlets as are commonly available in existing bulidings, can be combined to provide twice as much power than is available from each separate branch outlet without exceeding the power rating of each such branch outlet.
Existing branch-line circuits as commonly found in existing houses and buildings typically receive power from a power source such as a nearby power line through three lead-in conductors including two high voltage conductors, one at opposite polarity or phase from the other and a third grounded lead-in conductor substantially at ground voltage. In such branch-line circuits, at least one branch line is interconnected to each of the nominal or high voltage lead-in conductors and terminates in one or more such branch outlets, each branch outlet having at least two power-carrying contactors, one interconnected to the third grounded lead-in conductor and the other interconnected to one of the nominal voltage lead-in conductors.
In my copending application, embodiments are disclosed by which rated current from each of two such branch outlets is combined to provide double power at double voltage in a single combiner outlet connector. Thus, double the rated power available separately from each such branch outlet is combined by suitable contactor-selector means, to draw up to rated current from each of the two oppositely phased lead-in conductors of the branch-line circuit which accordingly have double voltage impressed therebetween
With such double voltage present in the circuit and in the combiner outlet connector, it is good practice to have suitable grounding means for safety purposes. Accordingly in my copending application such grounding is obtained by utilizing a third grounding contactor when available in the branch outlets being utilized, by incorporating in each electric input connector a third contactor, or by connecting the combiner circuit ground terminal to some other suitable independent grounding means.
Inasmuch as such third, grounded, contactor is not available in all existing houses and buildings, and to provide a separate grounding means is often of considerable inconvenience, a simpler, more convenient grounding means is needed.